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450

OLEINE  (OLEIC ACID)

2.  Unsaponifiable Substances.A preliminary test for these sub-
stances is as follows :   6-8 drops of the oleine and 5 c.c. of seminormal
alcoholic potash are boiled for two minutes in a test-tube and. then diluted
with 15 c.c. of water : in this way pure oleine yields a clear or almost imper-
ceptibly milky liquid (distillation oleine), whereas a turbid liquid is obtained
with oleine mixed with mineral oil.

To separate and estimate the unsaponifiable substances, the methods
indicated on p. 388 are used.

To ascertain if the unsaponifiable matter is composed of the hydro-
carbons naturally occurring in distillation oleine or of added mineral oil, the
rotatory power and the iodine number of the unsaponifiable matter are
determined : in the former case the value of [a]D is from + 4-8 to + 9-6
and the iodine number 62-69, whereas mineral oils have practically no
rotatory power or iodine number.

3.  Determination of the Solid Fatty Acids (Palmitic and Stearic).
This, may be effected by the methods indicated in the preceding chapter
(p. 384) or by determining the solidifying point of the oleine (see preceding
chapter, p. 418).    From the point of solidification obtained, the content
of stearine is deduced by means of de Schepper and Geitel's table, which
has been prepared with the aid of mixtures of pure oleine with solidifying
point 5-4 and stearine with solidifying point 48 :

TABLE   L
Content of Stearine in Oleine

Solidifying
	Percentage of
	Solidifying
	Percentage of
	Solidifying
	Percentage of

Point
	Stearine
	Point
	Stearine
	Point
	Stearine

(C.).
	(48).
	(C.).
	(48).
	( C.).
	(48).

6
	O'^s
	15
	6-6
	23
	157

7
	0-8
	1 6
	.   77
	24
	17-0

8
	1-2
	17
	8-8
	25
	1 8 -5

9
	17
	18
	9-8
	26
	20 -o

10
	'-5
	19
	II -2
	 "*7
	21-7

ii
	3'2
	20
	12 -I
	28
	23-3

12
	3-8
	21
	13-2
	29      ;     25-2
	
13
	47
	22
	14-5
	30            27-2
	
I4
	5-6
	
	
	
	
* *

A good oleine should have an acid number about 179, corresponding with
about 90% of free fatty acids, calculated as oleic acid. Oleines are however
found with 80-98% of free acids.

The content of neutral fat may vary from o to 20% (usually 10-15%).

The iodine number is usually 80-90. If it exceeds 90, the presence of Hnoleic,
linolenic and other less saturated acids derived from drying vegetable oils is
indicated.

The unsaponifiable substances should not exceed 2% in saponiftcation oleine,
but may reach 10% in distillation oleine.

In saponification oleine, up to 20 % of neutral fat and up to 2 % of unsaponi-
matter are permitted, and jn distillation oleine, up to 5% of neutral fat,al oleines